A β-diketo compound enabling keto-enol transformation is capable of forming a complex compound with aluminum in an enol structure. That is, there is produced an aluminum chelate compound as a compound containing a β-diketo group(s). Because an alkyl group(s) bonded to a β-diketo group(s) is usually included in a β-diketo compound, such aluminum chelate compound also has an affinity for many kinds of organic polymeric materials. For this reason, such aluminum chelate compound has been used in compositions containing organic polymeric materials, such as paints, adhesive agents and inks, and has endowed these compositions with various types of properties. For example, such aluminum chelate compound is used as a catalytic composition for a room temperature-curable resin.
As such a kind of aluminum chelate compound, there has been known, for example, a monoacetylacetonate aluminum bis (ethylacetoacetate) 76% isopropanol solution. Patent document 1 discloses, for example, a method for synthesizing such aluminum chelate compound. However, such known aluminum chelate compound often exhibits a low activity when used as a curing catalyst for a sealant or the like. That is, such known aluminum chelate compound may not necessarily be the most appropriate option depending on the intended use.
Meanwhile, as a room temperature fast-curable organopolysiloxane composition of a condensation curing type, there have been known a one-solution type where a rate of crosslinking due to hydrolysis is improved by using a curing agent on a base polymer which is an organopolysiloxane having both terminal ends blocked by hydroxy groups; and a two-solution type where a base polymer which is an organopolysiloxane having both terminal ends blocked by hydroxy groups and a crosslinking agent are packed separately.
There have been known various room temperature-curable compositions that can be cured to form elastomers at room temperatures. Particularly, a type of composition that releases an alcohol(s) when being cured does not generate an unpleasant smell and cause metals to corrode. Therefore, such a type of composition is preferably used in sealing materials, adhesive agents and coating agents for electronic devices.
As such a type of composition, there have been disclosed a composition consisting of a polyorganosiloxane having its terminal ends blocked by hydroxyl groups, an alkoxysilane and an organic titanium compound; a composition consisting of a polyorganosiloxane having its terminal ends blocked by alkoxysilyl groups, an alkoxysilane and an alkoxy titanium; a composition consisting of a linear polyorganosiloxane having its terminal ends blocked by alkoxysilyl groups and including a silethylene group(s), an alkoxysilane and an alkoxy titanium; and a composition consisting of a polyorganosiloxane having its terminal ends blocked by hydroxyl groups or a polyorganosiloxane having its terminal ends blocked by alkoxy groups and an alkoxy-α-silyl ester compound (Patent documents 2 to 5).
Although these compositions are superior in preservation stability, water resistance and moisture resistance, they have exhibited insufficient fast curabilities.
As described above, a polymer having a reactive alkoxysilyl group at its terminal ends is heretofore known. Since this polymer already has its polymer terminal ends blocked by alkoxysilyl groups, there can be obtained a composition exhibiting a superior preservation stability and a curability that does not easily change (deteriorate) with time. Further, a workability (viscosity, thixotropy) thereof can be arbitrarily adjusted; there can be formed a cross-linkage and an elastomer thereof by reaction with the water in the air; and superior properties (hardness, tensile strength, elongation at break) can also be achieved.
However, since an alcohol-type curable composition has a low reactivity with the water in the air as compared to heretofore known curable compositions of other curing types such as an oxime-type, an acetic acid-type and an acetone-type, restrictions are imposed on locations where an alcohol-type curable composition can be used.
In response, studies have been made on a functional group (linking group) adjacent to a reactive alkoxy group, and it has been reported that an a-alkoxysilylmethyl terminal end group is particularly highly reactive with the water in the air (Patent document 6). However, there exist downsides including a still insufficient curability; a negative impact inflicted on durability by the adjacent functional group (linking group); and a low restorability of a cured product.
In addition, by attempting to solve the problem of the curability, there arises another problem where yellowing occurs after performing an anti-UV discoloration test.